▎ 摘　　要

Electrochemically reduced graphene oxides (ERGO) are obtained under various reducing potentials in the phosphate buffer solution (PBS). Different characterization methods are used to analyse the changes of structure and surface chemical condition for graphene oxide (GO). The results show that GO could be reduced controllably to certain degree and its electrochemical activity towards VO2+/VO2+ and V3+/V2+ redox couples is also tunable using this environmentally friendly method. The catalytic mechanism of the ERGO is discussed in detail, the C=O functional groups other than the C-O functional groups on the surface of ERGO more likely provide reactive sites for those redox couples, leading to a more comprehensive understanding about the catalytic process than previous relevant researches. This controllable modification method and the ERGO as electrode reaction catalyst with enhanced battery performance are supposed to have promising applications in the all vanadium redox flow battery. (C) 2013 Elsevier Ltd. All rights reserved.